Solid state watch with magnetic setting

ABSTRACT

Disclosed is a solid state electronic wristwatch with no moving parts. The watch electronics are hermetically sealed in the watch case to be free of dust and moisture and the sealed components are resiliently mounted for improved shock resistance. Two setting switches and a demand switch within the casing are operated from outside the watch by permanent magnets, the demand magnet operating with a demand pushbutton. The setting magnet may be stored in the watch bracelet.

United States Patent 1 Bergey Apr. 2, 1974 SOLID STATE WATCH WITH MAGNETIC SETTING [75] Inventor: John M. Bergey, Lancaster, Pa. [73] Assignee: Time Computer, Inc., Lancaster, Pa. [22] Filed: Aug. 7, 1973 [2]] Appl. No.: 386,369

Related US. Application Data [62] Division of Ser. No. 138,557, April 29, 1971, Pat.

52 U.S. Cl. 58/50 R, 50/855 [51] Int. Cl. G04b 19/30, G04b 27/00 [58] Field of Search 58/23 R, 33, 34, 50 R, 58/855 [56] References Cited UNITED STATES PATENTS 3,129,557 4/1964 Fiechter 58/23 R X 3,485,033 12/1969 Langley ..58/50R 3,576,099 4/1971 Walton 58/23 R X 3,643,418

2/1972 Polin et al 58/855 Primary Examiner-Richard B. Wilkinson Assistant Examiner-Edith Simmons Jackmon Attorney, Agent, or Firm-LeBlanc & Shur [57] ABSTRACT Disclosed is a solid state electronic wristwatch with no moving parts. The watch electronics are hermetically sealed in the watch case to be free of dust and moisture and the sealed components are resiliently mounted for improved shock resistance. Two setting switches and a demand switch within the casing are operated from outside the watch by permanent magnets, the demand magnet operating with a demand pushbutton. The setting magnet may be stored in the watch bracelet.

3 Claims, 15 Drawing Figures PATENIEDAPR 2M4 3.800.525

' sum 1 UP 9 FIG. I

PMENIEDAPR 2:914 (800,525

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SOLID STATE WATCH WITH MAGNETIC SETTING .diodes of an electro-optic display. Low power consumption and small size and weight are achieved through the use of complementary MOS circuits to produce what is in essence a miniaturized fixed program computer. In particular, the present invention is directed to a solid state wristwatch of this type in which the active components'are completely sealed for longer life and which incorporates an improved read switchmagnetic setting arrangement.

Battery-powered Wristwatches and other small portable timekeeping devices of various types are well known and are commercially available. The first commercially successful battery-powered wristwatch is of the type shown and described in assignees U.S. Pat. No. Re26,l87, reissued Apr. 4, 1967, to John A. Van Horn et al for ELECTRIC WATCH. Electric watches of this type employ a balance wheel and a hairspring driven by the interaction of a current-carrying coil and a magnetic field produced by small permanent magnets.

ln recent years, considerable effort has been directed toward the development of a wristwatch which does not employ an electromechanical oscillator as the master time reference. ln many instances, these constructions have utilized a crystal-controlled high frequency oscillator as a frequency standard in conjunction with frequency conversion circuitry to produce a drive signal at a suitable timekeeping rate. However, difficulties have been encountered in arriving at an oscillatorfrequency converter combination having not only the required frequency stability but also sufficiently low power dissipation and small size to be practical for use in a battery-powered Wristwatch.

In order to overcome these and other problems, there is disclosed in assignees U.S. Pat. No. 3,560,998, issued Feb. 2, 1971, a crystal-controlled oscillator type watch construction using low power complementary MOS circuits. The oscillator-frequency converter combination of that patent is described as suitable for driving conventional watch hands over a watch dial or, alternatively, for selectively actuating the display elements of an optical display in response to the drive signal output of the converter.

ln assignees U.S. Pat. No. 3,576,099, issued Apr. 27, 1971, there is disclosed an improved watch construction in which the optical display takes the form ofa plurality of light-emitting diodes which are intermittently energized on demand at the option of the wearer of the watch. This assures a minimum power consumption and an increasingly long life for the watch battery. An improved watch construction of this general type incorporating solid state circuits and integrated circuit techniques is disclosed in assignees copending U.S. patent application Ser. No. 35,196, filed May 6, 1970 now U.S. Pat. No. 3,672,155.

The present invention is directed to an improved watch construction of the same general type as disclosed in the aforementioned application and patents and one which utilizes no moving parts to perform the 5 timekeeping function. The watch of the present invention consists of three major components, namely, a quartz crystal time base, a miniature time computer module, and a power supply or battery. These microminiature components are packaged in a conventional size wristwatch chassis or case. A tiny quartz slab is precisely cut to predetermined dimensions so that it vibrates at 32,768 Hz when properly stimulated by pulses from an electronic oscillator. The high frequency from the crystal time base is divided down to one pulse per second by utilizing a multi-stage integrated circuit binary counter. The time computer module counts the pulse train, encodes it into binary form, and then decodes and processes the result so as to provide the appropriate signals at display stations.

Situated on the front of the watch adjacent the display is a pushbutton demand switch which, when pressed, instantly activates the appropriate visual display stations. Minutes and hours are programmed to 5 display for one and one-quarter seconds, with just a touch of the demand switch. Continued depression of this switch causes the minute and hour data to fade and the seconds to immediately appear. The seconds continue to count as long as the wearer interrogates the computer module. Computation of the precise time is continuous and completely independent of whether or not it is displayed.

The watch display consists of a television screen-like colored filter which passes the cold red light from gal- 5 lium arsenide phosphide (GaAsP) light-emitting diodes. Preferably a 7 segment array forms each individual nilmbr at the appropriate moment at a brightness determined by a specially constructed dimmer or display intensity control circuit. This dimmer circuit utilizes one or more photo-detectors to measure ambient lighting conditions so the display intensity provides viewing comfort under all day or nighttime lighting conditions.

Important features of the present invention include a magnetically operated demand or read switch and magnetically operated hour set" and minute set" switches for setting the watch to the appropriate time. The hour set switch rapidly advances the hours without disturbing the accuracy of the minutes or seconds.

0 The minute set switch automatically zeros the seconds while it advances the minutes to the desired setting. The whole procedure, even though seldom required, takes a matter of a few seconds.

Because of the magnetic setting and magnetic interrogation, active components of the watch may be hermetically sealed to produce a unit that is shockproof and waterproof, regardless of the environment in which it is placed. Since there is no conventional stem for Winding or setting, the small shaft sealing problem is eliminated and no maintenance or repair is normally necessary since the active components are hermetically sealed and inaccessible to influences from the outside world. All solid state electronic components, including 5 the light-emitting diode displays, have a virtually unlim- Another object of the present invention is to provide a wristwatch which utilizes no moving parts for performing the timing function.

Another object of the present invention is to provide a solid state watch in which the active components of the watch are hermetically sealed.

Another object of the present invention is to provide a magnetically operated on demand display system for a solid state watch.

Another object of the present invention is to provide a solid state'wristwatch incorporating magnetic time setting.

Another object of the present invention is to provide a solid state wristwatch having a digital optical display which is virtually shockproof and waterproof.

Another object of the present invention is to provide a solid state wristwatch with no moving parts having improved operating characteristics and reduced cost.

These and further objects and advantages of the invention will be more apparent upon reference to the following specification, claims, and appended drawings, wherein:

FIG. 1 is a front view of a conventional size mans wristwatch constructed in accordance with the present invention;

FIG. 2 is a simplified block diagram of the major components of the solid state watch of this invention;

FIG. 3 shows a display element for the watch of the present invention in the form of a 7 bar segment construction of light-emitting diodes;

FIGS. 4, 4a, and 4b, taken together, are an overall block diagram of the electrical circuit for the solid state watch of FIG. 1;

FIG. 5 shows a modified watch circuit in which substantially all of the major electrical components of the watch are formed using large-scale integrated circuitry;

FIG. 6 is an exploded view of the wristwatch of FIG.

FIG. 7 is a cross section taken along line 66 of FIG. 1;

FIG. 8 is a bottom plan or rear viewof the watch of FIG. 1;

FIG. 9 is a cross section perpendicular to that of FIG. 7 taken along line 9-9 of FIG. 1;

FIG. 10 is an enlarged plan view of the demand button assembly of the watch of FIG. 1;

FIG. 11 is a cross section through the demand button assembly taken along line lll1 of FIG. 10;

FIG. 12 is a crosssection perpendicular to that of FIG. 11 taken along the line l2l2 of FIG. 10; and

FIG. 13 is a plan view of the flat demand button spring before it is formed into the curved shape shown in FIGS. 11 and 12.

Referring to the drawings, the novel watch of the present invention is generally indicated at 10 in FIG. 1. The watch is constructed to fit into a watch case 12 of approximately the size of a conventional mans wristwatch. The case 12 is shown connected to a wristwatch bracelet l4 and includes a display window 16 through which time is displayed in digital form as indicated at 20. Mounted on the case 12 is a demand switch pushbutton 18, by means of which the display 20 may be actuated when the wearer of the wristwatch l0 desires to ascertain the time.

In normal operation, time is continuously being kept but is not displayed through the window 16. That is, no time indication is visible through the window and this is the normal condition which prevails in order to conserve battery energy in the watch. However, even though the time is not displayed through the window 16, it is understood that the watch 10 continuously keeps accurate time and is capable of accurately displaying this time at any instant. When the wearer desires to ascertain the correct time, he-depressed the pushbutton 18 with his finger and the correct time is immediately displayed at 20 through the window 16. The hours and minutes are displayed through the window 16 for a predetermined length of time, preferably one and one-quarter seconds, irrespective of whether or not the pushbutton 18 remains depressed. The exact time of the display is chosen to give the wearer adequate time to consult the deisplay to determine the hour and minute of time. Should the minutes change during the time of display, this change is immediately indicated by advancement of the minute reading to the next number as the watch is being read. If the pushbutton 18 remains depressed, at the end of one and onequarter seconds, the hours and minutes of the display are extinguished, i.e., they disappear, and simultaneously the seconds reading is displayed through the window 16 immediately below the hours and minutes display 20. The advancing seconds cycling from 0 to 5 9 continue to be displayed through window 16 until pushbutton switch 18 is released.

FIG. 2 is a simplified block diagram of the principal components of the watch 10 of FIG. 1. The circuit comprises a time base or frequency standard 26 including a piezoelectric crystal to provide a very accurate frequency such that the frequency standard or oscillator oscillates at 32,768 Hz. This relatively high frequency is supplied by a lead 28 to a frequency converter 30 in the form of a divider which divides down the frequency from the standard so that the output from the converter 30 appearing on lead 32 is at a frequency of I Hz. The frequency converter 30 preferably comprises a binary counting chain of complementary MOS transistors of the type shown and described in assignees US. Pat. No. 3,560,998, the disclosure of which is incorporated herein by reference. The 1 Hz signal is applied by lead 32 to a display actuator 34 which in turn drives the displays 20 and 22 of the watch 10 by way of electrical lead 36.

- FIG. 3 shows a display station 38 forming one of the numerals of the hours and minutes display 20 and the seconds display 22. Each of these display stations (with the exception of the hours tens display as more fully described below) is preferably in the form of a 7 bar segment array of light-emitting diodes of the type shown and described in detail in assignees U.S. Pat. No. 3,576,099, issued Apr. 27, 1971, the disclosure of which is incorporated herein by reference. FIG. 3 shows 7 bar segments of light-emitting diodes 40, 42, 44, 46, 48, 50, and 52, all of elongated shape and arranged so that by lighting an appropriate combination of the bars or segments any of the numbers 0 through 9 may be displayed.

FIGS. 4, 4a, and 4b show an overall block diagram of the electrical circuit of the watch of the present invention. Reference may be had to assignees copending United States patent application Ser. No. 35,196, filed May 6, 1970 now US. Pat. No. 3,672,155, the disclotype shown and described in assignees US. Pat. No.

3,560,998, which acts as a divider, dividing the output by 2 i.e., a seven stage counter, to produce an output on lead 102 having a pulse repetition rate of 256 Hz. This signal is divided by 2 in counter 104, by 2 again in counter 106, by 8 (2 in counter 108, and by 4 (2 in counter 110.

An 8 Hz output on lead 112 from counter 108 is applied to a set-hold circuit 114 where the 8 Hz repetition rate pulse train appears as an output on lead 116. The 8 Hz signal on lead 116 is applied to a counter 118 where it is divided by 8 (2 to produce a 1 Hz output pulse train on lead 120. The l Hz pulse train is divided by in counter 122, divided by 6 in counter 124, divided by 10 again in counter 126, divided by 6 in counter 124, divided by 10 again in counter 126, divided by 6 again in counter 128, and the output of this counter is finally applied to counter 130 which divides by 12. The output of counter 122 appearing on leads 132, 134, 136, and 138 is a binary coded decimal 1248 code which is applied to the decoder-driver 140 which, in turn, energizes the tens digits of the seconds display indicated at 142. The ones digits of the seconds display indicated at 144 are similarly actuated from counter 124 by way of seconds decoder-driver 146. Similar decoder-drivers 148, 150, and 152 actuate the tens digits of the minutes display at 154, the ones digits of the minutes display at 156, and the hours display at 158. Counter 130 has five output leads to decoder-driver 152 for a purpose more fully described below. The other decoder-drivers 146, 148, and 150 are actuated by BCD 1248 codes from their respective counters 124, 126, and 128 in the same manner as decoderdriver 140 is actuated from counter 122.

As previously stated, in order to conserve energy, the light-emitting diodes are only energized on demand, i.e., when the pushbutton 18 of FIG. 1 is depressed by the wearers finger. Even when the button is depressed, the lights are not always continuously lit but instead, in order to conserve power, are intermittently lighted during less than full daylight conditions at a frequency sufficiently high to give the appearance of continuity due to the light retention properties of the human eye. The pulses for intermittently lighting or pulsing the seconds display are derived from a display control driver 160 which applies the ON-OFF pulses by way of lead 162 to the seconds decoder-drivers 140 and 146. Similar intermittent pulses from the display control drivers 160 are applied by lead 164 to the minutes decoder-drivers 148 and 150 and by lead 166 to the hours decoder drive 152. The exact frequency at which the displays are turned on and off while always sufficiently high to give the impression to the human eye of continuous light is determined by a light control circuit 168 which supplies a light control signal over lead 170 to display control drivers 160. The light control signal is either DC (full daylight) or a combination of a 64 Hz signal supplied from counter 106 by way of lead 172, a 128 Hz signal supplied by counter 104 by way of lead 174, and a 256 Hz signal supplied from the output of counter by way of lead 176. These signals are combined in the light control circuit 168 in a manner determined by the output signal on lead 178 to the light control circuit from ambient light sensors 180. These light sensors are in the form of three photo-transistors mounted on the face of the watch inside the viewing window and act to produce increased illumination from the light-emitting diodes during strong daylight conditions and less illumination from the diodes under nighttime or reduced light conditions. In the preferred embodiment, light'sensors 180 provide four different light levels from the light-emitting diodes so that the watch face'may be read with equal facility and comfort under all possible lighting conditions, while at the same time conserving energy at times when less light is needed from the diodes to make them visible, such as is the case when the watch is read in at least partial darkness.

As previously stated, the watch face is ordinarily not illuminated. The hours and minutes diodes only light up when the demand switch is depressed. Actuation of the demand button by the wearer causes the read switch 184 in FIG. 4 to close, causing the positive side of the power supply to be connected by way of leads 186 and 188 to the display control drivers 160. Energization of these drivers permits passage through them of the signal from the light control circuit 168 which is passed on to the decoder-drivers causing the minutes and hours displays to be illuminated. No output from the display control diodes 160 appears on lead 162 at this time and the seconds displays are not illuminated. Closure of the read switch 184 also applies B+ by way of lead 190 to set-hold circuit 114 which immediately resets a display timer 192 by way of lead 194. Display timer 192 is a divide by 10 counter and has applied to its input the 8 Hz pulse train on lead 112. This timer divides the 8 H2 pulse by 10 and after one and one-quarter seconds produces an output pulse on lead 196 which is applied to display control driver 160. This pulse causes the display control driver to change state, removing the output from leads 164 and 166 and causing the minutes and hours display to be extinguished. At the same time, the output is switched to lead 162 causing the seconds display to be illuminated simultaneous with the extinguishment of the hours and minutes display.

An important feature of the watch of the present invention lies in the fact that the hours may be set independently of the minutes and seconds and at a very rapid rate. Closure of hours-set switch switch 198 grounds one input of an hours-set circuit 200 by way of leads 202 and 204. Hours'set circuit 200 receives a 2 Hz pulse train from counter 1 10 by way of lead 206 and actuation of the hours-set circuit by closure of hoursset switch 198 causes the hours-set circuit 200 to pass the 2 Hz signal on lead 206 to counter by way of lead 208. Hours-set switch 198 is also connected to the display control drivers to cause an output to appear on leads 164 and 166 assuring that the hours and minutes are displayed when the hours are being reset during closure of switch 198. A minute-set switch 212 is connected by leads 214 and 216 to a minute-set circuit 218. As before, actuation of this circuit causes it to pass a 2 Hz pulse train on lead 220 from counter 110 by way of lead 222 to the divide by 10 counter 126 driving the minutes display. Minute-set switch 212 is likewise connected by lead 224 to display control drivers 160, again to insure an output on leads 164 and 166 during resetting.

In the watch of the present invention, actuation of the minute-set switch 212 automatically zeros the seconds display. The reason for this is that most time signals, such as those given over the radio and the like, are given on the hour or on the minute and in order to start the watch in synchronism with the correct time as given by such a signal, it is necessary that the seconds display be at zero at the time the radio tone or other time signal is heard. In order to accomplish this, the minute set switch 212 is connected by leads 214 and 216 and a further lead 226 to set-hold circuit 1 14. Energization of this'circuit from lead 226 produces an output pulse on output lead 228 which is applied to the reset terminals of counters 118, 122, and 124 by way of leads 229,

231, and 233, resetting these counters to zero and causing the seconds display to be automatically zeroed. Depressing read switch 184 unlocks the set time and begins the real time counting sequence.

FIG. 5 shows a modified embodiment of the solid state watch of the present invention, generally indicated at 230. In FIG. 5, like parts bear like reference numerals, and the overall construction of the watch in FIG. 5 is generally similar to the embodiment previously described. The principal modification incorporated in the embodiment of FIG. 5 is that the vast majority of the electrical components are formed from one or more large-scale integrated circuits, as indicated by the large integrated circuit block 232 in FIG. 5. Reference may be had to assignees copending United States patent application Ser. No. 138,547, filed Apr. 29, I971 now US. Pat. No. 3,714,867, and entitled SOLID STATE WATCH INCORPORATING LARGE-SCALE INTEGRATED CIRCUITS, in the name of Bruno M. Dargent, for a detailed description of the large-scale integrated circuit 232, the disclosure of that copending application being incorporated herein by reference.

In FIG. 5, the crystal oscillator 96 is of the type previously described and includes a piezoelectric crystal 234, a variable trimming capacitor 236, and a bias resistor 238. The active components of the oscillator are a pair of complementary MOS transistors connected to form an inverter and they are incorporated in the largescale integrated circuit 232. As in the previous embodiment, the oscillator preferably operates at a frequency of 32,768 Hz. The entire watch is powered from a conventional watch battery or power supply, indicated at 240, and the demand switch 184, the minute-set switch 212, and the hour-set switch 198 are all connected from the positive side of the battery 240 to the other or grounded side of the battery through the respective resistors 242, 244, and 246.

The modified embodiment in FIG. 5 includes a modified dimmer or display intensity control circuit comprising a capacitor 248, a resistor 250, a light sensitive resistor 252, a second resistor 254, and a second capacitor 256. These components in effect form a multivibrator which is triggered at a frequency of 64 Hz, which trigger signal is derived from an intermediate stage of the divider or frequency converter 30 incorporated in the large-scale integrated circuit 232. The pulse width of the multivibrator and therefore the duty cycle of the output from the multivibrator depends primarily on the value of fixed capacitor 256 and the value of the variable light sensitive resistor 252. For decreasing amounts of ambient light impinging upon resistor 252, as indicated by the arrow 258, the duty cycle of the multivibrator output is reduced and this output signal is applied to the displays 20 and 22 so as to vary their intensity with the amount of ambient light, i.e., the intensity is increased when the ambient light is great and the intensity of the light-emitting diodes is reduced when ambient light decreases.

The displays are controlled from the large-scale integrated circuit 232 by a pair of bipolar switches 260 and 262, labeled S and S respectively. These transistors connect the cathodes of the light-emitting diodes of the display to the negative side of the battery 240, i.e., to ground, so that the circuit to the light-emitting diodes is completed when the transistors 260 and 262 are in conduction. These transistors have their bases connected to the large-scale integrated circuit 232 through respective resistors 264 and 266. It is understood that when one of the switches S or S is turned on, the other is off and vice versa so that all displays are not simultaneously on. When switch S, (260) is turned on, this completes the circuit to the hours and minutes display diodes 20. If the demand button remains depressed, after one and one-quarter seconds switch 260 is turned off by the large-scale integrated circuit 232 and switch 262 is simultaneously turned on so that the hours and minutes display 20 disappears and the seconds display 22 immediately comes on. These displays receive timing signals from the large-scale integrated circuit 232 through the connecting leads generally indicated at 268.

FIG. 6 is an exploded view of the watch and FIG. 7 is a cross section through the watch of the present invention taken along line 77 of FIG. 1. The watch case 12 comprises a front plate 270, an inner cover 272, and a removable back plate 274. These three plates are preferably made from a non-magnetic metal material, such as that sold under the trade name l-Iavar. Between inner cover 272 and back plate 274 is the power supply in the form of a pair of 1.5 volt dry cells 276 and 278. The cells are preferably silver oxide batteries and are connected in series to produce an operating voltage of about 2.5 to about 3.2 volts DC. Back plate 274 carries a plurality of mounting springs 280 with projections 282 which snap into corresponding recesses in the front plate 270 for ready attachment and removal of the back plate so that access may be gained to the battery cells 276 and 278. The back plate is sealed by an annular rubber O-ring 284.

FIG. 8 is a bottom plan or rear view of the watch of FIG. 1 with portions shown in dashed lines and FIG. 9 is a cross section at right angles to the cross section of FIG. 7 taken along line 9-9 of FIG. 1. FIG. 10 is an enlarged plan view of the assembly for demand button 18. The battery cells are separated from back plate 274 by annular insulating washers 284 but have their negative side connected to the back plate and therefore grounded to the case by an electrically conductive cell connector 286. A similar cell connector 288 (FIG. 9) connected to the positive side of the power supply is electrically connected to a positive cell lead 290 which passes through a suitable glass seal 292 to establish electrical connection to the electronic circuit indicated generally at 294 mounted on circuit substrate 296. Trimming capacitor 236 and the piezoelectric crystal 234 are also mounted on the substrate 296. Placed in the viewing window over the light-emitting diodes is a light filter 298. The filter is fabricated from a ruby to insure relative scratch and break resistance. A solderable metal material is deposited along the edge of the filter to aid in the solder-sealing of the filter to the front plate 270 as indicated at 300 in FIG. 9. The pink ruby is preferably coated with a red dyed clear epoxy paint on its inside surface to provide a deep red color which transmits most of the 6,500 Angstrom wavelength light from the light-emitting diodes carried by the electronic substrate 296. Inner cover 272 is solder-sealed to front plate 270 around its edge, as indicated at 302 in FIG. 9, and this inner cover carries four mounting posts, two of which are illustrated at 304 in FIG. 9. These posts or studs are welded to inner cover 272 and the substrate 296 is held against these shoulder studs by means of screws 306. Both sides of the substrate rest against a resilient shock absorbent material 308 and 310 to provide maximum protection against severe shocks encountered when dropping the' watch. The crystal can 234 and trimming capacitor 236 are all similarly protected by soft potting compound between the substrate and their assembled position as indicated at 312 and 314, respectively.

As can be seen, the electronics 294 is hermetically sealed all the way around between inner cover 272 and front plate 270. This hermetic seal acts as protection to the electronics and also prevents condensation of water vapor on the filter 298. The hermetically sealed cavity is provided by solder-sealing the filter to the front plate and solder-sealing the inner cover to this plate. The battery compartment is outside this cavity and is protected from the outside world by the case back or back plate 274 and the O-ring gasket 284. Electrical connections of the battery to the electronics are provided by glass-to-metal sealed feedthrough connectors as indicated at 292.

An important feature of the present invention resides in the fact that the read or demand switch 184, the minute-set switch 212, and the hour-set switch 198 are all magnetically operated in such a way that the electron ics 294 remains hermetically sealed. These three switches are shown in dashed lines in FIG. 8 and are preferably in the form of reed switches. There are several significant advantages in utilizing a permanent magnet operated reed switch to perform the hours, minutes and demand readout functions in the watch. First, the miniature switches are glass encapsulated, hermetically sealed devices which have a proven history of high reliability of this type of application. Secondly, no through-holes are required in the watch case so true hermetic sealing is simplified. Also, actuation of the switches requires a deliberate activity on the part of the wearer so that inadvertent operation is minimized. These switches are positioned in the watch as illustrated in FIG. 8 and attached to the substrate 296 by a soft potting compound, as illustrated, for example, at 316 in FIG. 9 for the hours-set switch 198. These switches are preferably of the type identified as MINI-2 switches manufactured by Hamlin, Inc. of Lake Wills, Wis, or equivalent. A switch pull sensitivity of between and ampereturns is desirable for the demand switch, while 35 to 40 ampereturns is desirable for both the hour and minutes set switches.

As best seen in FIG. 8, the front plate 270 of the watch case is provided with a first elongated setting slot 318 adjacent hour-set switch 198 and a second setting slot 320 adjacent the minute-set switch 212. A portion of the setting slot 318 is illustrated in solid lines in FIG. 9. It is understood that the minute-set switch slot or recess 320 is of similar construction. These two recesses or slots, one adjacent the hour-set switch and the other adjacent the minute-set switch are dimensioned so that a long cylindrical or square magnet can be placed into this recess when a change in setting time is desired. In the preferred embodiment, the setting magnet takes the form of a permanent magnet made from Alinco V material with dimensions of 0.500 inch long by 0.062 inch square. This produces a field of about 700 gauss.

As best seen in FIG. 7, the demand switch 184 is supported from the substrate 296 in a manner similar to the other switches, i.e., by a soft potting compound as illustrated at 322. FIG. 10 is a plan view of the pushbutton assembly 18, FIG. 11 is a cross section through the pushbutton assembly taken along line 1l-11 in FIG. 10, FIG. 12 is a cross section at right angles to that of FIG. 11 taken along line 12l2 of FIG. 10, and FIG. 13 shows the flat pushbutton spring before it is formed into a curved spring shape.

The pushbutton assembly is constructed so as to retain the hermetic seal about the electronic components of the watch. The pushbutton assembly comprises an elongated pushbutton proper 324 slidably received through a suitable aperture 326 in the front plate 270 of the watch case. Press fit into a circular recess in the center of the pushbutton 324 is a permanent magnet 328 formed in the shape of a right circular cylinder. Recess 326 is stepped to form a shoulder 330 which cooperates with an annular flange 332 on the lower end of pushbutton 324 to limit the upward or outward movement of the pushbutton. The plate shoulder 330 and annular flange 332 are preferably separated by an annular gasket 334 made of silicone.

The inner end of aperture 326 is closed off by a flat rectangular plate 336 made of brass or other suitable non-magnetic material. Brass plate 336 is soldered for a hermetic seal all the way around its edge to the inner surface 338 of front plate 270 as indicated at 340 in FIGS. 11 and 12. In this way, the pushbutton 324 and magnet 328, while mounted on the front plate, are sealed externally of the chamber carrying the watch electronics. Resting on top of brass plate 336 is a substantially rectangular arched or curved spring 342 which urges the pushbutton 324 and the magnet 328 carried by it upwardly or outwardly in the direction of the arrow 344 in FIG. 11. Spring 342 is preferably made of Havar or other suitable non-magnetic metallic material and, while its ends 346 and 348 rest on top of brass plate 336, it is symmetrically curved or arched about the centerline 350 of the pushbutton assembly so that its center is spaced approximately 0.030 inch from the top of brass plate 336. FIG. 13 shows the l-Iavar spring 342 in plan view while it is fiat and before it is formed into the arched or curved configuration illustrated in FIGS. 11 and 12. By way of example only, the spring may have a thickness of approximately 0.0024 inch. The demand magnet 328 which is press fit into the recess in pushbutton 324 is about 0.070 inch longand about 0.090 inch in diameter and utilizes cobalt platinum (CoPt) to produce a field of about 1,300 gauss.

It is apparent from the above that the present invention provides an improved timepiece construction and particularly a timepiece having sufficiently small size,

weight and power consumption for use as a conventional man s wristwatch. Important features of the present invention include a resilient shock-free mounting arrangement, a completely hermetically sealed assembly so that the electronics, display and other major components are completely sealed from atmospheric effects, a magnetically operated demand or read switch, and a pair of magnetically operated setting switches for setting the watch time. The setting permanent magnet may conveniently be stored in a suitable recess in the watch bracelet when not in use or may otherwise be carried on or adjacent the watch or in a suitable recess provided in the watch case. If desired, it is possible to paint the substrate and light reflecting materials in the vicinity of the light-emitting diodes a dark flat black. This improves readout visibility by providing maximum contrast ratio between the lightemitting diodes and their background. The piezoelectric crystal for the oscillator is preferably contained in its own hermetically sealed vacuum can to reduce its series resistance, improve its activity for any given drive current, and to minimize the natural aging effects of the crystal. In the preferred embodiment, the power supply is formed of two silver oxide cells in a standard size container operating at a nominal voltage of about 3 volts, but it is understood that any conventional wristwatch power supply may be utilized. As illustrated in FIG. 7, the electrical cells 276 and 278 are preferably mounted in a cell holder 352 mounted on the outside or backside of inner cover 272.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A wristwatch comprising a watch case of nonmagnetic material, timekeeping means in said case including a electro optical digital time display and a magnetic field responsive switch for setting said display, said case including a recess adjacent said switch whereby said switch may be actuated by the insertion of a permanent magnet into said recess from outside said case.

2. A wristwatch according to claim 1 including a second magnetic field responsive setting switch in said case, said case having a second recess adjacent said second switch.

3. A wristwatch according to claim 1 including a magnetic field responsive demand switch in said case for activating said display upon demand, and a permanent magnet movably mounted on said case adjacent said demand switch.

a UNITED-STATES PATENT OFFICE V 5 CERTIFICATE OF CORRECTION I Patent No. 3,800,525 Dated April 2 1974 Inventofl John M, Bergey It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4,: line 18, "deisplay" should read -'-display-- Column 5 line 60; "drive should read --driver- Column 9, line 50, "reliability of" should read --reliability in-- Signedand sealed this 1st day of October 1974.

(SEAL) Atvtest:

McCOY M. GIBSON JR; c. MARSHALL DANN Attesting Officer Commissioner of Patents PIA-i050 I UNITED-STATES PATENT OFFICE CERTIFECATE ()F CORfiECTION Patent No. 3 ,5 Dated p il 2, 1974 4 Ihventor(s) Jflhn M. Brgey It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 18, deisplaly" should read '-disp1ay-- Column 5 line 6O, "drive should read --driver-- 7 Column 9, line 50,- "reliability of" should read r--reliability 'in--.

Signed and sealed this 1st day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR; c0 MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A wristwatch comprising a watch case of non-magnetic material, timekeeping means in said case including a electro optical digital time display and a magnetic field responsive switch for setting said display, said case including a recess adjacent said switch whereby said switch may be actuated by the insertion of a permanent magnet into said recess from outside said case.
 2. A wristwatch according to claim 1 including a second magnetic field responsive setting switch in said case, said case having a second recess adjacent said second switch.
 3. A wristwatch according to claim 1 including a magnetic field responsive demand switch in said case for activating said display upon demand, and a permanent magnet movably mounted on said case adjacent said demand switch. 